<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
 class Set{
  constructor(){
   this.item = {}
  }
   has(value){
    return this.item.hasOwnproperty(value)
  }
   
  add(value){
    if(this.item.has(value)) return false
    this.item[value] = value
    return true
  }
   
  remove(value){
    if(this.item.has(value)) return false
     delete this.item[value]
     return true
  }

  clear(){
    this.item = {}
  }
 
  size(){
     let count = 0
    for(var value in this.item){
      if(this.item.has(value))
      count++
    }
   return count

  //  return Object.keys(this.item).length
  }
  
  values(){
    // return Object.keys(this.item)

    let keys = []
    for(var value in this.item){
       keys.push(this.item[value])
    }
  }
   

 }









  </script>
</body>
</html>